Method for making concrete building units



Nov. 9, 1948. A. HENDERSON METHOD FOR MAKING CONCRETE BUILDING UNITS 2Sheets-Sheet 1 Filed Oct. 1, 1946 l/l/I/l/IIIIIIIIIIII Nov. 9, 1948. A.HENDERSON 2,453,223

METHOD FOR MAKING CONCRETE BUILDING UNITS Filed Oct. 1, 1946 I 2Sheets-Sheet 2 Patented Nov. 9, 1948 BUILDING Albert Henderson.Pittsburgh, Pa., assignor, by

mesne assignments, to The Cemenstone Corporation, Pittsburgh, Pa., acorporation of Pennsylvania Application October 1, 1946, Serial No.700,501

1 Claim. (Cl. 25-154) This invention relates to the manufacture of'precast concrete building units such as wall members having surfaceswhich are exposed in the finished building.

In my copend'ing application Serial No. 657,497, filed March 27, 1946, Ihave disclosed a mold for making concrete building members includingspaced side walls resting on a base and adapted to be clamped together.It is an object of this present invention to provide an improved methodof manufacture in order to produce units havin flawless surfaces asremoved from the mold and to prevent damage thereto between manufactureand erection. v

In molding precast building units of concrete, holes are left in theouter surfaces as a result of the formation of bubbles, which seriouslymar the appearance of the units. These holes cannot be repaired readilyand remain as permanent defects in the surface. In addition, precastunits are subject to cracking and breakage of their corners duringshipment and handling. They also frequently become soiled or otherwisemarred or discolored.

I have invented a novel method for making precast building units wherebythe aforementioned objections are largely avoided. In a preferredpractice, I cast the units in crates formed of suitable wooden membersdisposed in the mold to form a liner. T-he crate protects the units frombreakage during handling. I sheath the mold side walls with an absorbentfabric such as bur-- lap or the like. This serves several purposes. Ittends to absorb water from the member being molded and gives it a dense,hard surface. It also prevents the formation of bubbles and the holesresulting therefrom. The fabric serves as an outer coating to protectthe units from soiling or discoloration so that when it is stripped offat the time of erection or after erection a perfect product with fresh,clean surfaces is available. Alternatively, the fabric may be left onthe units to provide a wall finish. It provides a surface which is welladapted to receive paint or a finished coat of plaster.

A complete understanding of the invention may be obtained from thefollowing detailed description which refers to the accompanyingdrawings, illustrating a preferred embodiment and practice. In thedrawings,

Figure 1 is a partial transverse section through a mold for the castingof a plurality of concrete building units;

Figures 2, 3 and 4 are transverse sections through a series of palletsof various widths having sealing gasket strips along their edges;

Figure 5 is a section through one of the gaskets to enlarged scale;

Figure 6 is a horizontal section through an end wall for use with themold in Figure 1;

Figure 7 is a sectional view taken on the plane of line VII-VII ofFigure 6;

' Figure 8 is an end view of one of the wooden members forming theshipping crate disposed in thCi mold;

Figure 9 is a horizontal section through the crate showing the end.pieces and the bottom piece;

Figure 10 is a side elevation of a completed unit having its end andbottom edges protected by the members forming the crate and its sidessheathed in fabric;

Figure 11 is a transverse section taken along the line of XIXI of Figure10;

Figure 12 is a view similar to Figure 10 showing a modified form ofcrate; v

Figure 13 is an endelevation thereof: and

Figure 14 is a partial transverse section through a storage and agingchamber.

Referring in detail to the drawings, and for the present to Figures 1through 5, a mold for casting concrete units indicated generally at l0comprises abase I I having spaced side walls l2, l3 and I4 restingthereon adapted to be secured together by any suitable means. The base-II has pipe coils.

I 5 embedded therein to provide for radiant heating of the mold. Thewalls i2, i3 and it are reinforced concrete slabs with their upper edgesarmored by channels Hi. It will be understood that the group of sidewallsfillustrated at Figure 1 is duplicated in a. continuous series tothe desired extent of the overall width of a complete gang mold. Thewall l3 has transverse supporting angles 11 secured to the bottomthereof. 1-

beams l8 adjusted to the desired height by blocks.

i8a rest on the angles [1 and are adapted to support pallets on whichthe units are cast between the side walls. In the left-hand moldcompart- I ment between the walls l3 and i4 I have shown a liner orcrate including a wooden bottom member iii-and end members 20. Thesemembers have nails driven therethrough as at 2| adapted to becomeembedded in the unit to hold the crate thereon during shipment. When theunit is ready for erection, the crate members may be readily stripped011?. The crate members have ribs 22 and grooves 23 adapted respectivelyto form grooves andtst-ongues in the side and end edgm of the ingconcrete therebetween.

edges thereof. As shown more clearly in Figures 2 through 4, palletslike that shown at 24 are 5 provided in a variety of widths such as 8",12" and 16". The sealing gaskets 25 are of rubber and have a'curved face28 adapted to engage the mold side walls. When compressed the gasketface 26 flattens out forming a tight seal.

The gaskets have vacuum cups 26a spaced along their faces 26. When thegaskets are pressed against the side walls of the mold, these vacuumcups grip the mold wall and hold the. gasket tightly thereto. When themold is opened up and the side walls moved slightly apart to permit theremoval of the unit cast therebetween, the gaskets move with the moldwalls, sliding on the plates 24 to the extent of the lateral movement ofthe side walls. This prevents dirt from accumulating in the jointsbetween the pallets and the mold wall. The upper surface 21 of thegasket is adapted to form a bevel on the lower corner of the unit beingcast. A groove 28 forming the gasket is adapted to accommodate the 25edge of the plate 24.- The latter is provided with pins 29 at intervalstherealong to engage the side walls and maintain proper spacingtherebetween.

' The gasket has holes 30 formed therein to accommodate the pins 29.

The ends of the mold compartments are defined by end walls 3| shown indetail in Figures 6 and 7. Each end wall is a length of I-beam standingvertically on the pallet, the flanges 32 having gaskets 25 removablyapplied thereto. The web 5 23 of the. length Of I-beam is coped out asat 84. The width of the flanges, of course, is such that the' gasketsthereon make tight sealing engagement with the mold side walls.

In casting units in the apparatus described above, I apply a sheathing35 of absorbent fabric such as burlap to the mold side walls beforecast- Conveniently, the sheathing is applied before the bottom member IQof the crate or the pallets 24 are put in place and the side wallsclamped thereagainst. The fabric sheathing may be secured to the edgesof the bottom and end crate members [9 and 20 as by tacking. The fabricis also secured to the upper edges of the mold side walls by anyconvenient means to prevent sagging. When the pallets such as shown at24 are used, the fabric may be secured to the mold wall and usedrepeatedly, instead (at being removed with the units, and

remaining thereon as a protective cover. Instead of burlap, I may useother fabrics such as muslin, or a fabric woven from glass fiber. In anycase, the material should be porous enough to absorb excess water andair from the concrete to prevent the formation of bubbles. 4 6 When themembers are installed, the fabric sheathing may befstripped oil or itmay be left permanently adhering thereto. In the latter case, it iscomposed of material of a suitable color to provide a decorative finishor is painted when installed. It may also serve as a base for a finishcoat of plaster. In addition to the bubble formation, the absorption of.water by the fabric sheathing makes the concrete denser on the surfaceand prevents checking. The sheathing, of

' course, serves to protect the unit from soiling or being otherwisemarred, and also insures proper curing since it holds a supply of waterand prevents dehydration of the units at the surface. The'sheathing may.be applied to all four suro of installation.

- 4 faces of the unit. In

sheathing may be subjected to a spray of colored plastic or rubber-onleaving the mold, thereby sealing the unit against loss of moistureduring curing. I v

Instead of casting the units vertically as shown in Figure l. I mayprovide a crate having a. fabric sheathing on one side and dispose thecrate horizontally with the fabric side down, and cast the concrete inthe crate and thereafter cover the upper surface unit with fabricsheathing. The fabric sheathing left on the units may be suitablywaterproofed as desired. 1

Figures 8 and 9 show the details of the crate which serve to protect theedges of the units from breakage during shipment prior to installation.

Figures 10 and ll'show a .complete unit 36 with the crate members I! and20 and the fabric sheathing l5 thereon. It will be apparent that a unitso made is already boxed and wrapped for shipment as it comes from themolds.

Figures 12 and 13 show a slight modified form of crate including, inaddition to the bottom and end members l9 and 20, a pair of spaced topmembers 31. These members are shaped to form the tongue on the upperedge of the unit, and the space between the members affords room for thecasting of the concrete. This construction.

0 obviously, provides a crate extending around all four edges of theunit. Rods 38 for reinforcing the unit may be assembled with the crate,the end members 20 of the crate having holes to receive the ends of therods 38. The crate members thus serve in a reinforcing position and therods to brace the crate members.

Figure 14 illustrates an enclosure for storing units as cast eitherduring curing or until needed for erection. The enclosure comprises abase 39 having embedded heating coils 40 for radiant heating, side walls.4l and a cover 42 hinged to one of the side walls. The base 39 has adepression 48 providing a pool of water for humidifyins the interior ofthe enclosure. Precast units such as slabs 44 are stood on edge inspaced relation on sills 45 laid in the recess of 43. When the cover 42is closed, grooves 46 therein accommodate the tongues on the upper edgesof the members and serve to maintain them in properly spaced relation. 1

It will be apparent from the foregoing that the invention provides anapparatus and method for making concrete building unitshaving numerousadvantages over the existing practice and equipment. The inventionpermits the manufacture of a unitwhich is already boxed and wrapped asit comes from the mold so that it is protected against damage orsoiling. The crate enclosing the unit may readily be stripped off at thetime The fabric sheathing may be stripped off orleft on if desired toprovide a decorative surface, a base for paint or a finish plaster coat.The absorbent fabric sheathing also improves the quality of the productby avoiding holes resulting from formation of bubbles, and increasingthe density of the concrete adjacent the surface. The fabric also tendsto prevent cracking or checking of the concrete and is advantageous inthe curing because it holds a supply of water to prevent dehydration byevaporation from the surface. The fabric may be removed from the unitafterit is erected onthe job so that the surface of the unit is keptfree from job dirt.

The apparatus of my invention also has m this one, it constitutes a, bagfor receiving the concrete as cast. The fabric portant advantages. Thepallets and end walls are simple and inexpensive yet sturdy, durable andeasily adjusted. The storage enclosure mainheated air aroundthe unitswhich causes nonuniform hardenin'jg on opposite sides.

Although I have illustrated but a preferred practice of my invention andcertain modifications, it will be understood that changes in theprocedure and construction disclosed can be made without departing fromthe spirit of the invention or the scope" of the appended claim.

I claim:

In the art of making precast concrete building units, thesteps'including positioning on a mold an open faced box with a flexiblewrapper disposed across an open face of the box, casting a plasticcementitious mix within the box and against said wrapper to form abuilding unit and when the mix has hardened removing from the mold theassembly of building unit, box and wrapper so that the building unit ascast is already boxed and wrapped adapting it to be transported whileprotecting against soiling or discoloration the face thereof disposed'against the Number Name Date 248,722 Driscoll Oct. 25, 1881, 640,653 GuyJan. 2, 1900 681,700 Himmelwright Sept. 3, 1901 775,588 Warden Nov. 22,1904 916,796 Simpson Mar. 30, 1909 1,324,027 Block Dec. 9, 19191,525,797 Blum Feb. 10, 1925 1,554,586 Lake Sept. 22, 1925 1,684,624Hayden Sept. 18, 1928 1,708,555 Smith Apr. 9, 1929 1,744,309 HendersonJan. 21, 1930 2,007,063 Rolland July 2, 1935 2,040,732 Foster May 12,1936 2,220,448 Henderson Nov. 5, 1940 2,294,556 Henderson Sept. 1, 19422,310,400 Crane et a1 Feb. 9, 1943 2,363,226

wrapper without necessitating wrapping after casting.

ALBERT HENDERSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Brund Nov. 21, 1944

